12/02/2005

What is going on this week at the NY Post?

The NY Post is still one of my favortite newspapers, but I am not sure what is going on this week at the NY Post regarding guns (see here and here). The NY Post has always been the one New York City newspaper that was willing to provide a different perspective on the gun issue.

Incorrect claims about the data in More Guns, Less Crime

I have received an email comparing my work to that of Steve Levitt's regarding claimed coding errors in More Guns, Less Crime. Of course, this discussion is not very accurate.

1) There are no coding errors in the data used in “More Guns, Less Crime.” The book used crime data from 1977 to 1996, and as far as I know, no academics have claimed that there were any coding errors in that data. An interesting and useful Stanford Law Review article by Plassmann and Whitley added an additional four years to the data and the problem arose in this additional data. Overall, less than 200 cells out of 7.5 million cells were accidentally left blank. More important, the results that Plassmann and Whitley noted were the results which they thought were the correct ones were not affected at all by this minor change in the data.

There are a few points to make. I am not sure that such a story could occur in the US because of all the regulations on how toy guns look here. In addition, I am not sure how much longer this could go on at in South Africa because legitimate gun ownership continues to be forced down dramatically by the government, it will be harder to convince criminals that the toy gun is real. Finally, I wonder whether a child like this would ever receive such a reward. In my book, The Bias Against Guns, I discuss multiple cases where young children used real guns to save lives and those cases got little publicity and no rewards were given out as far as I can tell.

Sorry for making such a long post here, but I wanted to give non-statisticians at least a rough idea of what was required for john Donohue and Steve Levitt to miss seeing whether they had included fixed effects in their regressions on abortion. The two thoughtful authors from the Boston Fed mentioned the "programming oversight" done by Donohue and Levitt in their abortion research. I still believe that saying that is "being much too nice," but I will leave it to readers to decide what level of sloppiness is involved in this research. Here is an abortion regression with fixed effects (though I have three types of fixed effects rather than the two used by the Boston Fed people). It is hard for me to see how this could have been missed. If one looks at these regressions, it is just hard to see how someone could miss having included them. The state-year interactions discussed by Foote and Goetz would add up to ((51*number of years)-1) to the list of control variables. I only wish that Donohue and Levitt had provided me with their regressions and all their data when I first asked for this six years ago. Their refusal to provide this information is at best extremely unfortunate. The obvious thing is that they should be ashamed for not providing this information in a timely manner when it was asked for.

Here are two simple regressions. Obviously more control variables can be included, but I decided to just show the simplest case from my paper with John Whitley. Notice how in this case fixed effects change the coefficient sign on the abortionpop variable. Including an absorb statement can eliminate one set of these fixed effects from being reported and thus make this point less obvious, but the general point is still the same.

[Update: An email from Carl Moody indicates that Donohue is giving out a regression file that accounts for fixed effects in at least one of the sets of estimates. The way that this is done indicates that they do not surpress the print out of the estimates and thus one would see whether fixed effects had been estimated. In any case, while I am very glad to see this now being made available, it would have been useful 4, 5, or 6 years ago when I was asking for the information.]Update 2: It should also be made clear that despite whatever sloppiness occurred Donohue and Levitt have acknowledged the coding error and agree that correcting the error and using arrest rates suggests no effect of legalizing abortion on crime.

My own work concentrated on murder rates, but I also included fixed effects. Donohue and Levitt never provided us with all their data or their regressions and would never answer any questions that we had so I just assumed that they had included fixed effects from the beginning. It would have been nice if they had provided us with this same information years ago.

Suppose one exercises at the moderate level: per year that is 130 hours = 52 (weeks)*5 (days)*.5 hoursover 50 years that is: 6,500 hours

There are 5,840 waking hours in a year. 8,175 over 1.4 years. At any reasonable interest rate, in terms of purely longevity, there is a strong negative return to exercise. For this to pay off, one must really enjoy the process of exercise or that it greatly improves the quality of life.

Beyond all that is the issue of the type of people who exercise. My guess is that the people who exercise generally tend to be more educated and have other characteristics (e.g., being married because they take care of themselves) that are associated with longer life expectancies. There is no mention that the study controls for such factors as income, education, and marriage.

More Crime Problems in UK: Surge in unsolved crimes

If people don't think that reporting the crime to the police is less and less likely to accomplish anything, this can result in reported crime falling farther below actual crime rates. This increase in reported crime could thus underestimate the true increase in crime. It is also a reason that crime rates will increase if criminals have less to worry about. Part of the increase in unsolved crimes is consistent with the increase in gang related crime in the UK. Overall, it raises additional questions about people in the UK being able to rely on law enforcement for protection.